Power semiconductor devices, such as power MOSFETs are commonly used in high frequency switching power conversion systems. In many applications the body diode of the power MOSFET is alternately biased between conduction and blocking states. During forward bias of the body diode, charge is stored in the neutral regions adjacent to the PN junction.
Before the body diode can return to a blocking state, the charge stored in the neutral regions adjacent to the PN junction must be extracted or neutralized. The process of extracting or neutralizing charge is known as “reverse recovery.”
The extraction and neutralization of body diode charge can result in power loss which lowers the power conversion efficiency of the semiconductor device. Therefore, it is advantageous if the total charge reverse recovery charge (Qrr) and the characteristic time necessary to extract or neutralize the charge (trr) are minimized. In prior art embodiments, an external Schottky diode is placed in parallel with the semiconductor device to minimize recovery losses. Since the Schottky diode has a lower forward voltage drop than the PN diode, the inductor current flows primarily through the Schottky diode, which has fast recovery characteristics. However, the placement of the Schottky diode results in increased circuit costs. Additionally, the placement of the Schottky diode requires additional board space.
Accordingly, a need exists to minimize the body diode reverse recovery time in semiconductor devices to reduce power loss and promote power conversion efficiency in the semiconductor device.